Our previous interaction studies identified a phenomenon in which 12-month-old infants protest when their mothers direct positive attention toward a doll, treated like an infant. Infants' protests suggest perturbation, possibly due to their interpreting maternal behavior as representing emotional unavailability, and may be an early form of jealousy. Following up on these results, the two studies being proposed aim to: Document "jealousy" responses in younger infants; Ascertain whether jealousy responses differ from negative reactivity shown in perturbing situations, Identify whether jealousy inducement is predominantly associated with a discrete emotion expression; and Determine whether individual differences are predicted by infant or maternal characteristics. Study 1 will address the feasibility of jealousy in younger infants by implementing our jealousy inducement paradigm with infants in the age range of 6- to 9-months. Infants will be exposed to four conditions of maternal unresponsiveness. In two, their mothers, and a then a stranger, will attend to a picture book; and in two additional episodes their mothers, and then a stranger, will attend to a doll. Cross context comparisons of infants' negative facial expressions, vocal distress, and struggling will suggest jealousy if infants are found most disturbed by the condition in which their mothers attended to a doll. Study 2 will address more detailed features of infant jealousy by observing styles and intensities of infants' facial expressions in three perturbations, consisting of: maternal separation, mothers adopting a "still face" and a jealousy inducement situation in which mothers will be physically present and expressing positive affect toward a doll as if it was a real infant. Additionally, mother-infant, face-to-face interactions will be observed before and after the perturbations. Cross-context and cross-emotion comparisons will assess the predominance, stability and intensity of emotion expressions and whether individual differences are predicted by maternal and/or infant characteristics. We believe that jealousy will be suggested by increased disturbances when infants observe their mothers attending to a doll, and demonstrated in a fashion similar to that observed in the other situations of maternal unavailability. We expect that for most infants, the predominant response to jealousy inducement will be anger, but for others, sadness or fear will predominate. Individual differences and intra-individual stability in negative reactivity will suggest variations in affective processing and features of temperament, respectively, and may be precursors to later dimensions of jealousy in intra- and inter-personal functioning.